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You are here:Home » Molecular Biology » MB-Enzymes » Proteinase K

Proteinase K


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A non-specific serine protease, Proteinase K will inactivate nucleases during native mRNA and DNA preparation. Recommended for high molecular weight nucleic acids from mammalian and microorganism sources. Used in the preparation of genomic DNA from bacteria. Active in the presence of SDS.
Catalog #P9100
Specific Activity (Protein) 30 units/mg dry weight
Unit DefinitionOne unit liberates 1umole of Folin positive amino acids, measured as Tyrosine, in 10 minutes at 37°C, pH 7.5, using urea-denatured hemoglobin as the substrate.
Working Concentration3ul of a 20mg/ml solution per 1.5ml of bacterial culture. Dissolve 20mg/ml Proteinase K in 10mM Tris HCl, pH 7.5, 1mM calcium acetate.
Optimum pH 7.5-12, using denatured hemoglobin as substrate.
SpecificityIn addition to cleavage of peptide bonds, it is able to catalyze peptide amide hydrolysis. Proteinase K is inactivated by diisopropyl fluorophosphate (DFP) or phenyl methane sulphonyl fluoride (PMSF). Chelating agents such as citrate and EDTA have no affect on the enzyme activity.
Storage and StabilityLyophilized powder may be stored at 4°C. Stable for 12 months after receipt at 4°C. Reconstitute, aliquot and store at -20°C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
Important NoteProteinase K solution contains Ca2+ and glycerol and is stable for 6 months. Shipping and short term storage can be at ambient temperature.
Although calcium ions do not affect the enzyme activity, they do contribute to its stability when present at a concentration of 1-5 umoles. An interesting characteristic of proteinase K is that it retains its activity in the presence of SDS or urea. (0.5-1% SDS and 1-4 M urea). Raising the temperature of the reaction from 37°C to 50-60°C can increase the activity several fold. A special feature of proteinase K is its ability to digest native proteins, thereby inactivating enzymes such as DNase and RNase without recourse to a denaturation process.
CAS Number39450-01-6
Molecular Weight28.9kD
SourceTritirachium album limber
FormSupplied as a lyophilized powder
Important NoteThis product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications without the expressed written authorization of United States Biological.
Alternate namesEC=; Tritirachium album limber

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